The present invention relates to a power tug for moving small aircraft at airports and the like. More particularly the present invention relates to a power tug using a commercially available portable electric drill to drive a gear and wheel assembly capable of rapid attachment to small aircraft front wheel axles and nose struts. The present embodiment is steerable.
Moving small aircraft on the ground is often necessary when the aircraft is serviced or taken to a hanger or brought out. In the past, the motor has been started and the aircraft""s own power has moved it from one place to another. This, of course, presents a potential danger from the rotating propeller. It also produces unnecessary wear and stress on the motor when it is operated for just a short while.
As an alternative, aircraft tugs have been employed, much like the large tugs that move commercial jet aircraft and the like. However, this requires a significant investment in equipment costs for operating the tug. It also requires having someone available to operate the device and/or train small aircraft owners to use the machine.
It would be of great advantage if a simple, efficient device could be developed that would permit owners to move their own planes without worrying about safety concerns from the motor of the plane.
One such device has been proposed. Olson U.S Pat. No. 4,915,185 discloses a portable aircraft moving device using a portable electric drill. The drill output shaft is linked to a worm gear to mount temporarily to the front wheel of the airplane above the airplane wheel. While the drawings of this patent are clearly not intended to be to scale, the size of the airplane and the operator distort the difficulties of moving aircraft that may weigh several thousand pounds. Olson requires a drive wheel in the device to engage the aircraft front wheel and use that wheel to push or pull the aircraft. One additional drawback of Olson is that it places frictional stress on the nose wheel. It is not adaptable to all aircraft, requiring a specific axle adapter for each make or model.
Other patents have also found use for portable electric drills. Hawgood U.S Pat. No. 4,156,315 discloses a dolly for maneuvering trailers, again using a worm gear.
Perkins U.S Pat. No. 4,280,578 teaches the use of an electric drill for a walker for the disabled, a far less substantial weight and effort than aircraft. Perkins also uses a worm gear arrangement.
Finally, Hurt U.S Pat. No. 3,713,501 employs an electric drill to alternatively move a belt to elevate the hand truck up or down stairs or move the wheel axle of the hand truck on flat ground. None of these other devices suggest a simple, effective method for moving small aircraft without frictional engagement with the nose wheel of the aircraft and without having separate fittings for each make or model of the plane being moved.
In my copending continuation-in-part, a solution to the problems of the prior are is described and claimed. This invention improves on my prior invention by modifying the design, to make the device steerable, producing substantial advantages including the ability to move much heavier aircraft because of the steerable features.
Other advantages will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, the present invention provides a tug for moving small aircraft, usually single engine, on the ground while the motor of the airplane is off.
The tug device includes two parts that are fastened together prior to use, in one or more orientations depending on the specific aircraft being taxied. One component comprises a power transmission column having a battery powered drill having a variable output, mounted on the upper end of the column and a drive wheel at the other end. A drive shaft engages the drill and a speed reducing gear box to drive the unit. The unit is steered by movement of a handle on the column.
The second component comprises a frame having a first and second end defining a generally u-shape configuration. A fixed position trunion mounted on the first end of the frame for engagement with an aircraft. A rotating engaging member is mounted on the other end of the frame, the engaging member having an engaging trunion for engagement with an aircraft. A control member is provided for moving the engaging trunion into and out of engagement with the aircraft. Dolly wheels are on the frame for free wheeling the unit.
The unit is assembled using a connector mount for connecting the frame to the power column to position the fixed position trunion and engaging trunion in position to engage an aircraft in at least one position. In the preferred embodiment, there are two positions so that the tug can work on open front or nose wheels and a second position for engagement with the wheel strut when the wheel is covered, such as with a faring.
Finally, the device includes a pivot means tucked into the hollow cavity of the wheel without changing the general overall appearance of the tug of this invention. A supporting structure between the pivot pin and the main frame is located underneath a gearbox speed reducer. The steerable feature is accomplished using an independent arm piece as described hereinafter.